Marine sessile organisms such as barnacles and mussels are causing serious financial damage by attaching to ships and vessels and lowering their sailing abilities, attaching to fishing nets and damaging them, and attaching to water supply and drain pipes of electric power plants and lowering their cooling efficiency. Conventionally, organotin compounds have widely been used as chemicals for preventing marine organisms from attaching to fishing nets and ship bottoms. Use of organotin compounds, however, is being regulated because of their strong toxicity and effect as environmental hormone. Since many of alternative compounds also contain copper or zinc, there is a concern about their adverse effects on the environment, and thus there is a demand for development of safe chemicals with less toxicity.
Regarding organic solvent extracts of red algae laurencia sp., it has been reported that laurinterol and isolaurinterol obtained from Laurencia okamurae possess a barnacle attachment inhibitory activity (Non-Patent Document 1).
It has also been reported that elatol and deschloroelatol obtained from Laurencia rigida have a barnacle attachment inhibitory activity (Non-Patent Document 2).
There is also a report that an organic solvent extract of Laurencia obtusa inhibited attachment of sessile organisms including barnacles in field tests (Non-Patent Document 3).
It has not been known so far, however, that organic solvent extracts of Laurencia sp. from Omaezaki, Laurencia sp. from Hachijojima, Laurencia nipponica, and Laurencia thyrsifera have a barnacle attachment inhibitory activity.
Furthermore, compound Laurencin has been known to be isolated from Laurencia nipponica (Non-Patent Document 4), and the total synthesis of it has also been reported (Non-Patent Document 5). Its biological activities, however, have not been reported so far.
Furthermore, compound Thyrsiferol isolated from Laurencia thyrsifera was also reported (Non-Patent Document 6). The compound was also isolated from Laurencia obtusa, and is known to have cytotoxicity (Non-Patent Document 7). It has not been known so far, however, whether it has an attachment inhibitory activity against cypris larvae of barnacles.
Furthermore, while it has been reported that compound Magireol A was isolated from Laurencia obtusa (Non-Patent Document 8), its biological activities have not been known so far.
In addition, Laurencia sp. from Omaezaki and Laurencia sp. from Hachijojima, are Laurencia sp. that have not been identified so far. Compound Omaezallene isolated from Laurencia sp. from Omaezaki and compound Hachijojimallene A isolated from Laurencia sp. from Hachijojima are compounds that have not been known so far, either.    [Non-Patent Document 1] Ryu, Geonseek; Yoon, Oh Sub. Studies on marine natural antifoulant laurinterol. Han'guk Hwankyong Uisaeng Hakhoechi (2003), 29(3), 1-8.    [Non-Patent Document 2] R. de Nys, T. Leya, R. Maximilien, A. Afsar, P. S. R. Nair, and P. D. Steinberg, The need for standardised broad scale bioassay testing: A case study using the red alga Laurencia rigida, Biofouling, 10(1-3)213-224 (1996).    [Non-Patent Document 3] Da Gama B A P, Pereira R C, Carvalho A G V, et al, The effects of seaweed secondary metabolites on biofouling. Biofouling 18(1)13-20 (2002)    [Non-Patent Document 4] Irie, T., Suzuki, M. 1965. Laurencin, a constituent from Laurencia species; Tetrahedron Lett. 1965: (No. 16) 1091-1099.    [Non-Patent Document 5] Fujiwara, Kenshu; Yoshimoto, Saori; Takizawa, Ayumi; Souma, Shin-ichiro; Mishima, Hirofumi; Murai, Akio; Kawai, Hidetoshi; Suzuki, Takanori. Synthesis of (+)-laurencin via ring expansion of a C-glycoside derivative. Tetrahedron Letters (2005), 46(40), 6819-6822.    [Non-Patent Document 6] Blunt, J. W.; Hartshorn, M. P.; McLennan, T. J.; Munro, M. H. G.; Robinson, Ward T.; Yorke, S. C. Thyrsiferol: a squalene-derived metabolite of Laurencia thyrsifera. Tetrahedron Letters (1978), (1), 69-72.    [Non-Patent Document 7] Suzuki, Teruaki; Suzuki, Minoru; Furusaki, Akio; Matsumoto, Takeshi; Kato, Arata; Imanaka, Yoshihiko; Kurosawa, Etsuro. Constituents of marine plants. 62. Teurilene and thyrsiferyl 23-acetate, meso and remarkably cytotoxic compounds from the marine red alga Laurencia obtusa (Hudson) Lamouroux. Tetrahedron Letters (1985), 26(10), 1329-32.    [Non-Patent Document 8] Teruaki Suzuki, Satoshi Takeda, Minoru Suzuki, Etsuro Kurosawa, Arata Kato, and Yoshihiko Imanaka, Cytotoxic squalene-derived polyethers from the marine red alga Laurencia obtuse (Hudson) Lamouroux. Chemistry Letters (1987) pp. 361-364.